Digital capacitive touch panel structure

ABSTRACT

The present invention discloses a touch panel structure formed by an anti-scratch surface layer and a capacitive sensor layer, and a transparent lamination layer is used for pasting the two into a panel. The capacitive sensor layer includes an X-axis first transparent conductive layer and a Y-axis second transparent conductive layer formed on both sides of a transparent plastic carrier to provide a touch panel structure having the advantages of a relatively low material cost, a light weight, an easy manufacturing and molding, a better lamination yield and a flexible and break-free feature.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation application of U.S. Ser. No.12/496,703, filed Jul. 2, 2009, the disclosure of which is incorporatedherein by reference in its entirety.

BACKGROUND OF THE INVENTION

(a) Field of the Invention

The present invention relates to a novel structure of a touch panel, inparticular to a touch panel structure having the advantages of arelatively low material cost, a light weight, an easy manufacturing andmolding process, a better lamination yield and a flexible and break-freefeature.

(b) Description of the Related Art

Touch panel is mainly divided into resistive, capacitive, surfaceacoustic wave, or optical IR touch panel according to its differentsense method. Among them, resistive and capacitive touch panels are usedwidely, wherein the structure of the resistive touch panel seems asandwich, the top layer is an transparent conductive plastic film andthe down layer is a conductive carrier, dot spacers are filled withbetween them and a voltage of 5V is introduced. The top layer will touchthe down layer when it is touched (or knock little) by a finger or apen, and a delta voltage (ΔV) will be produced. An A/D controller willconverts the delta voltage into a digital signal provided for a computerto compute (X,Y)-axes positions to achieve a excellent positionaccuracy.

Basically, the capacitive touch panel improves the scratch resistance ofthe resistive touch panel and solves the circuit break issue that willcause a failure of the touch panel if the top layer (the transparentconductive film) is scratched seriously. With reference to FIG. 1 for abasic structure of a conventional capacitive touch panel, the outermostlayer is an anti-scratch layer 11 made of glass, and the second layer isa capacitive sensor structure 12 covered by the anti-scratch layer 11,and the capacitive sensor structure 12 adopts both sides of a singlesheet glass 121 to form an X-axis-wise capacitive sensor layer 122 and aY-axis-wise capacitive sensor layer 123 (or adopts two glass pieces toform the X-axis-wise and Y-axis-wise capacitive sensor layers on asingle side of each glass piece, such that a uniform electric field isproduced between the X-axis-wise capacitive sensor layer 122 and theY-axis-wise capacitive sensor layer 123 as shown in FIG. 2 and providedfor sensing a weak current of a human body to achieve a touch controleffect.

In the conventional touch panel as shown in FIG. 1, the anti-scratchlayer 11 and capacitive sensor structure 12 are glass substrates.Although the capacitive sensor structure 12 can be manufactured byetching (a photolithography process included in color filtered) and thepattern by this way is not visible, the cost of the required equipmentsand manufacturing processes are too high and not cost-effective.Furthermore, a transparent lamination layer 13 is used as a linkingbridge or is pasted to a surface of an LCD panel 16. The glass-to-glasslamination method, which the both layer are so hard, not only results ina poor lamination yield, but also has difficulties to get a goodaccuracy and arises into a risk of breaking the panel easily.

There is another type of touch panel structures as shown in FIG. 3available in the market, and a capacitive sensor structure 14 of thisconventional touch panel includes two transparent conductive plasticfilms 141, 142 formed on an X-axis-wise capacitive sensor layer and aY-axis-wise capacitive sensor layer respectively, and a transparentlamination layer 13 is used to paste the two transparent conductiveplastic films 141, 142. Similarly, an anti-scratch layer 11 made ofglass is pasted to the top of the capacitive sensor structure 14 by thetransparent lamination layer 13, and another transparent conductiveplastic film 15 as an EMI shielding function is pasted to the bottom ofthe capacitive sensor structure 14.

However, the conventional touch panel as shown in FIG. 3 has arelatively complicated structure and high material and manufacturingcosts, and the capacitive sensor layers of the transparent conductiveplastic films 141, 142 are produced by a traditional screen printingetching method, and whose capacitive sensor pattern has a relatively lowprecision. In addition, the anti-scratch layer 11 is also made of glass,and has the same issues of a low lamination yield r, a high cost and arisk of breaking the panel easily. The touch panel is formed by stackingand combining a plurality of sensor layers and insulat layers, not onlyresulting in a thicker panel, but also decreasing the light transmissionof the touch panel substantially.

SUMMARY OF THE INVENTION

Therefore, it is a primary objective of the present invention to providea touch panel structure with the advantages of a relatively low materialcost, a light weight, an easy manufacturing and molding process, abetter lamination yield and a flexible and break-free feature.

To achieve the foregoing objectives, the present invention provides atouch panel structure comprising an anti-scratch surface layer and acapacitive sensor layer, wherein a transparent laminated layer is usedas a linking bridge laminated between the top and down layers, and theanti-scratch surface layer can be a transparent plastic film that hasbeen treatmented by hard coating process, and the capacitive sensorlayer includes an X-axis first transparent conductive layer and a Y-axissecond transparent conductive layer formed on both sides of atransparent plastic carrier respectively, and first and secondtransparent conductive layers include a plurality of X-axis first senseelements and Y-axis second sense elements alternately arranged with oneanother, such that each sensor element in the same axis is electricallyconnected, and insulated from each sensor element in another axis, and auniform electric field is produced between the X-axis first transparentconductive layer and the Y-axis second transparent conductive layer. Inaddition, the whole touch panel structure includes a transparentconductive plastic film as an EMI shielding function which is pasted tothe bottom of the capacitive sensor layer and allows the whole touchpanel structure to be operated at an noise-free environment.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a conventional touch panelstructure;

FIG. 2 is a schematic view of an electric field produced by an X-axiscapacitive sensor layer and a Y-axis capacitive sensor layer;

FIG. 3 is a cross-sectional view of another conventional touch panelstructure;

FIG. 4A is a cross-sectional view of a touch panel structure inaccordance with a first preferred embodiment of the present invention;

FIG. 4B is a schematic view of first and second transparent conductivelayers of the present invention;

FIG. 5 is a cross-sectional view of a touch panel structure inaccordance with a second preferred embodiment of the present invention;and

FIG. 6 is a cross-sectional view of a touch panel structure inaccordance with a third preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to FIGS. 4A and 4B for a touch panel structure inaccordance with a first preferred embodiment of the present invention,the touch panel structure comprises an anti-scratch surface layer 20 anda capacitive sensor layer 30.

The anti-scratch surface layer 20 is made of a transparent plastic filmwhich has been treatment by the hard coating. In general, a thinpolyethylene terephthalate (PET) panel is used as a substrate. Thecapacitive sensor layer 30 includes an X-axis first transparentconductive layer 311 and a Y-axis second transparent conductive layer312 formed on both sides of a transparent plastic carrier 31respectively, wherein the first and second transparent conductive layers311, 312 include a plurality of X-axis first sense element 3111 andY-axis second sense elements 3121 alternately arranged in an array form,such that each sense element in the same axis is electrically connectedand insulated from each sense element in another axis. In other words,the first sense elements 3111 in the X-axis are electrically connectedwith one another, and the second sense elements in the Y-axis areelectrically connected with one another, and each first sense element3111 is insulated from each second sense element 3121, so as to producean a uniform electric field between the separated X-axis firsttransparent conductive layer 311 and Y-axis second transparentconductive layer 312.

In an embodiment, the capacitive sensor layer 30 is pasted to the bottomof the anti-scratch surface layer 20 by a transparent lamination layer50 and protected by a shielding effect of the anti-scratch surface layer20. The capacitive sensor layer 30 further includes a conductive layer40 pasted to the bottom of the capacitive sensor layer 30 reaching anEMI shielding function to maintain the whole touch panel structure to beoperated at an EMI free environment. The conductive layer 40 is made ofan indium tin oxide (ITO) conductive film and pasted to the bottom ofthe capacitive sensor layer 30 by the transparent laminated layer 50.

With reference to FIG. 5 for a second preferred embodiment of thepresent invention, the touch panel structure comprises an anti-scratchsurface layer 20 and a capacitive sensor layer 30.

The capacitive sensor layer 30 includes a Y-axis second transparentconductive layer 312 formed on a side of a transparent plastic carrier31 as shown in the figure, and the Y-axis second transparent conductivelayer 312 is disposed on the top of the transparent plastic carrier 31,and an X-axis first transparent conductive layer 311 is pasted to thetop of the Y-axis second transparent conductive layer 312 by atransparent lamination layer 50 to produce a uniform electric fieldbetween the X-axis first transparent conductive layer 311 and the Y-axissecond transparent conductive layer 312. Of course, the X-axis firsttransparent conductive layer 311 can be disposed on a substrate 313(which can be a polyethylene terephthalate (PET) film) and pasteddirectly onto the top of the Y-axis second transparent conductive layer312. In other words, the X-axis first transparent conductive layer 311is positioned at the bottom of the substrate 313. Alternatively, thesubstrate 313 can be pasted directly onto the top of the Y-axis secondtransparent conductive layer 312 according to a third preferredembodiment of the present invention as shown in FIG. 3. In other words,the X-axis first transparent conductive layer 311 is positioned on thetop of the substrate 313.

In an embodiment, the capacitive sensor layer 30 is pasted to the bottomof the anti-scratch surface layer 20 by a transparent lamination layer50 and protected by a shielding effect of the anti-scratch surface layer20. In addition, the capacitive sensor layer 30 further includes aconductive layer 40 pasted on the bottom of the capacitive sensor layer30 as shown in FIGS. 5 and 6, and the conductive layer 40 is coated atthe bottom of the transparent plastic carrier 31 directly by a methodsuch as a low temperature sputtering method.

Compared with the conventional touch panel structure, the touch panelstructure in accordance with present invention comes with a relativelysimpler structure to reduce the material cost and the weight of thewhole touch panel structure substantially, and thus the presentinvention is suitable for the development of a thin and lightweightdesign.

In this preferred embodiment, the transparent plastic carrier 31 can befrom different plastic material such as polycarbonate (PC),polymethylmethacrylate (PMMA), polyethylene terephthalate (PET) or anyother cyclic olefin copolymer, and preferably a polycarbonate resinwhich is polycarbonate (PC) in this embodiment, and the transparentplastic carrier preferably must has a thickness greater than 0.5 mm, sothat there will be have a good impact-resistance, high thermalstability, high gloss, effective bacteria suppression effect, andexcellent flame-resistance and anti-smudge.

Therefore, a polycarbonate (PC) sheet used as a substrate of thecapacitive sensor layer 30 in the present invention not only facilitatesthe optical lamination, but also provides a better lamination yield andan easy maintenance.

Since the polycarbonate (PC) sheet has an excellent mechanical propertyfor supporting the whole touch panel, such that the whole touch panelstructure can be flexible without the risk of being broken easily.

The X-axis first transparent conductive layer 311 and the Y-axis secondtransparent conductive layer 312 are indium tin oxide (ITO) transparentconductive films formed on both sides of the transparent plastic carrier31 respectively by a low temperature sputtering method.

Compared with the conventional touch panel structure, the touch panelstructure of the present invention comes with a relatively simplerstructure to reduce the material cost and the weight of the whole touchpanel structure substantially, and thus the present invention issuitable for the development of a thin and lightweight design.

Compared with the conventional touch panel structure, the touch panelstructure of the present invention has the following advantages:

1. The whole touch panel structure is relatively simpler to reduce thematerial cost and the weight of the whole touch panel structuresubstantially.

2. The transparent plastic carrier 31 of the capacitive sensor layer ismade of an industrial plastic material which is a polycarbonate (PC)substrate for facilitating an optical lamination with a polycarbonate(PC) sheet, and thus resulting in a better lamination yield and aneasier maintenance.

3. The transparent plastic carrier 31 of the capacitive sensor layer 30is a polycarbonate (PC) sheet, not only having a good mechanicalproperty for supporting the whole touch panel, but also providing abetter flexibility of the whole touch panel structure to prevent it frombeing broken easily.

4. The capacitive sensor layer 30 having the X-axis first transparentconductive layer 311 and the Y-axis second transparent conductive layer312 formed on both sides of the transparent plastic carrier 31respectively can overcome inaccurate alignments of the X-axis andY-axis.

5. Unlike the conventional touch panel structure having at least oneglass substrate, the whole touch panel structure is made of a plasticsubstrate, and thus the invention has the advantages of providing aneasy molding process and reducing the risk of breaking the panel.

While the invention has been described by means of specific embodiments,numerous modifications and variations could be made thereto by thoseskilled in the art without departing from the scope and spirit of theinvention set forth in the claims.

1. A touch panel structure, comprising: an anti-scratch surface layer;and a capacitive sensor layer, pasted to the bottom of the anti-scratchsurface layer, and having an X-axis first transparent conductive layerand a Y-axis second transparent conductive layer formed on both sides ofa transparent plastic carrier respectively, and the first and secondtransparent conductive layers including a plurality of X-axis firstsense elements and Y-axis sense elements alternately arranged in anarray form, such that each sense element in the same axis is connectedelectrically and insulated from each sense element in another axis. 2.The touch panel structure of claim 1, wherein the transparent plasticcarrier is made of an industrial plastic material selected from thecollection of polycarbonate (PC), polymethylmethacrylate (PMMA),polyethylene terephthalate (PET) and any other cyclic olefin copolymer,and the industrial plastic material is preferably a polycarbonate resin.3. The touch panel structure of claim 1, wherein the transparent plasticcarrier has a thickness preferably greater than 0.5 mm.
 4. The touchpanel structure of claim 1, wherein the X-axis first transparentconductive layer is an indium tin oxide (ITO) transparent conductivefilm, and the Y-axis second transparent conductive layer is an indiumtin oxide (ITO) transparent conductive film.
 5. The touch panelstructure of claim 1, wherein the X-axis first transparent conductivelayer is formed on a side of the transparent plastic carrier by a lowtemperature sputtering method.
 6. The touch panel structure of claim 1,wherein the Y-axis second transparent conductive layer is formed onanother side of the transparent plastic carrier by a low temperaturesputtering method.
 7. The touch panel structure of claim 1, wherein theanti-scratch surface layer is made of a polyethylene terephthalate (PET)film that has been treatmented by hard coating.
 8. The touch panelstructure of claim 1, wherein the capacitive sensor layer is attached tothe bottom of the anti-scratch surface layer by a transparent laminationlayer.
 9. The touch panel structure of claim 1, wherein the capacitivesensor layer includes a conductive layer pasted to the bottom of thecapacitive sensor layer for providing an EMI shielding function.
 10. Thetouch panel structure of claim 9, wherein the conductive layer is madeof an indium tin oxide (ITO) conductive film, and pasted to the bottomof the capacitive sensor layer by a transparent lamination layer.